Embodiments of the present invention relate generally to insulative materials and, more particularly, to insulative materials configured to change shape in response to changes in temperature, as well as associated methods for forming the insulative materials.
Insulative materials are utilized in a wide variety of applications. For example, spacecraft and other air vehicles commonly include insulation for protecting the occupants and/or the cargo from the relatively extreme temperatures that may otherwise be experienced. As another example, clothing, such as jackets, may include one or more layers of insulation to assist the wearer in remaining warm when in a cold climate. While the insulation utilized by spacecraft, clothing and other applications may generally be suitable for relatively static thermal conditions, the insulation may become unsuitable or unnecessary as the thermal conditions change, such as in instances in which the ambient temperature becomes warmer, in instances in which the wearer of an insulated jacket exercises or otherwise increases their metabolic rate or in instances when the radiant heat load changes, as would occur when going from shade into full sun. Indeed, since insulated clothing generally has a fixed thermal resistance, wearers may become too hot or too cold as the ambient temperature changes, the metabolic rate of the wearer varies or the radiant heat load changes. In instances in which the wearer becomes too hot, the wearer can remove the clothing, but is then burdened with having to carry or otherwise account for the clothing which has been removed.
Some clothing has been designed in an effort to alter the thermal resistance of the clothing as conditions change. For example, some skiwear includes vents that can be opened or closed. When open, the vents allow air to flow around the insulation layer to cool the wearer. As such, a skier can open the vents in their clothing as the temperature increases, as the metabolic rate of the skier increases following one or more runs, or as the radiant heat load increases. Conversely, the skier can close the vents to restrict airflow around the insulation layer so as to allow the skier to remain warmer, such as in instances in which temperature decreases, the metabolic rate of the skier drops or the radiant heat load decreases. A ski jacket has also been developed having pull strings that, when pulled, displace insulating material within the jacket and, therefore, alter the insulation characteristics of the jacket.
While the foregoing skiwear does provide at least some modification of the insulation characteristics of the skiwear, this skiwear still only provides acceptable insulation over a relatively small range of temperatures, metabolic rates and radiant heat loads and, as such, is unable to fully accommodate greater changes in either temperature, metabolic rate and/or radiant heat load. Further, the foregoing skiwear requires manual intervention by the wearer, which may be undesirable in some circumstances or which may be overlooked or forgotten by the wearer in other instances.
Accordingly, it would be desirable to develop an improved insulative material that is configured to provide variable insulation characteristics, thereby providing appropriate insulation even as the thermal characteristics change, such as with changing temperature, metabolic rate and/or radiant heat load.